Generally, thermoplastic resins have good processability and mechanical properties such that the resins have been widely used in various products including electronic goods. Some of these thermoplastic resins have been used as flameproof resins after adding a flame retardant in order to decrease the danger of fire while using them. One method for imparting flame retardancy is to add halogen containing compounds or phosphorus compounds as a flame retardant to thermoplastic resins. However, since a flame retardant itself may not provide an acceptable level of flame retardancy, a flame retardant can be used together with a flame retardant aid. For example, bromine containing compounds can be used with antimony containing compounds, and phosphorus containing compounds can be used together with a char-forming agent such as polycarbonate resin or polyphenylene ether resin in order to impart flame retardancy.
Filler can also be added both to reduce the cost of raw materials and to improve processability. Examples of the filler for a thermoplastic resin include calcium carbonate, talc, silica, mica, barium sulfate, and the like. However, because the filler has a high specific gravity, the addition of the filler increases the specific gravity of the composition, the weight per volume, and eventually, the weight of the molded articles. Therefore, the addition of the filler can significantly undermine the cost reducing effect of the filler.
Furthermore, when a filler is added to a resin, it can significantly lower flame retardancy such that it can be difficult to obtain a desirable flame retardancy in a flameproof resin.